The present invention relates to a method of producing filter-tipped cigarettes.
As described, for example, in British Patent n. 2,241,866, filter-tipped cigarettes are produced on a filter assembly machine internally defining a path along which elongated tobacco items are fed in a direction perpendicular to their axis. The above known filter assembly machine is supplied at the input with a succession of first tobacco items consisting of double cigarette portions which, moving transversely along said path and through a cutting station, are each cut into two coaxial single portions. The portions in each coaxial pair are then parted axially and separated by the insertion of a double filter which, together with the respective two single portions, forms a second tobacco item hereinafter referred to as a "group". Inside a rolling station and by means of a gummed strip, the component elements of each second tobacco item are connected integral with one another to form a third tobacco item hereinafter referred to as a "double cigarette", and wherein the central portion of said strip encloses the double filter, and the end portions of the strip enclose the respective facing ends of the two cigarette portions.
To experts in the field, the rolling action to which the groups are subjected to form the double cigarettes is known to be a highly critical phase in that rolling over and above a given maximum speed, depending directly on the output capacity of the filter assembly machine, results in tobacco spill from the open ends of the two cigarette portions.
Also, for a given output capacity of the filter assembly machine, rolling speed is known to depend directly on the spacing with which the succession of groups is fed to the rolling station.
In connection with the above, it should be pointed out that, for convenience in terms of design and, more particularly, to conform with more widely used cigarette production lines, the standard spacing with which the groups are fed to the rolling station is relatively wide (roughly 37.7 mm). If, on the one hand, this facilitates a number of handling operations upstream from the rolling station, on the other it is directly responsible for large part of the rolling speed.